In electronics, a partial discharge is a localized dielectric breakdown of a small portion of an electrical insulation system under a high voltage stress, which does not bridge the space between two conductors. Partial discharges within solid insulation systems are typically caused by a failure in the insulation system, for example due to dirt, contamination, or defects. Another common cause of partial discharges within solid insulation systems is the presence of voids within the insulation systems, which function as capacitors that discharge small amounts of energy to ground at a 60 Hz frequency.
In the field of high voltage, high current electrical system maintenance and repair, a full discharge (and thus an equipment failure) can be deadly to a nearby technician. Since partial discharges typically precede full discharges, a device capable of detecting partial discharges would be useful in the environments in which such technicians work.
Certain methods of detecting partial discharges are known. For example, it is known that partial discharges produce several signatures that can be used to characterize and locate issues. Some signatures that may be checked for in the field are the presence of a transient earth voltage, and a high frequency acoustic signal. By locating these signatures, technicians may locate and diagnose faults in the field, but detection of these signatures requires expensive, specialized equipment. In addition to being expensive, this equipment requires specialized training that technicians may not have.
Therefore, the development of new devices to detect partial discharge that are easy to use as well as relatively economical to produce is desirable.